GLOBAL WARMING: DIRECT AND INDIRECT EFFECTS

R-453A has a direct GWP of 1,765, and R-22 has a direct GWP of 1,810. A GWP of 1,765 means R-453A traps 1,765 times as much heat per kilogram as CO2 does over a 100-year period. This GWP value measures the direct effect of a refrigerant when it is released into the atmosphere. A leaking refrigeration or air conditioning system is a good example of a direct emission, which has a direct effect on global warming. See Graph 1 for a comparison of R-453A’s GWP and the GWPs of some other popular HFC-based R-22 retrofit refrigerants.

The direct measurement of global warming for a refrigerant gas alone can be a bit misleading, however. If the refrigerant never leaks into the atmosphere and stays confined in the HVACR system, the gas will have no direct effect on global warming. When figuring the total effects of global warming, many factors come into play, including the application the refrigerant is used for, the efficiency of the HVACR system, duration of operation, leakage of refrigerant from the system, and other application-specific variables. These important factors play a major role in determining the direct and indirect effects of global warming.

As an example, if an air conditioning system is a bit undercharged or overcharged, it will run longer to reach the desired indoor temperature set point. Assuming the electricity supplied to the equipment originated from a fossil fuel, the equipment’s inefficiency from the incorrect refrigerant charge caused a longer run time, thus more electricity usage. Longer run times indirectly cause more CO2 to be generated in supplying electricity to the equipment and would be considered an indirect effect of global warming. Conversely, if a system has a higher EER or SEER, the system will use less electricity over time, generating less CO2.

A refrigerant’s thermal dynamic efficiency and physical properties also come into play when measuring the total effects of global warming. R-453A has excellent thermal dynamic performance when used as a refrigerant in refrigeration and air conditioning applications. The blend has similar cooling capacities and a slightly higher coefficient of performance (COP) when compared to R-22. Because of this, it has the benefits of lower energy consumption than R-22. The mass flow rate and compression ratio of R-453A are also very similar to R-22, and R-453A has a slightly lower discharge temperature than R-22. Because of the higher efficiencies of R-453A, it has a somewhat low total equivalent warming impact (TEWI). The TEWI takes into consideration both the direct and indirect effects of global warming as equivalent CO2 emissions. So, even though R-453A has a direct GWP of 1,765, it is counterbalanced by its lower TEWI because of its associated higher efficiencies.

LUBRICANT AND SERVICING

R-453A is compatible with the traditional lubricants and newer synthetic lubricants in the HVACR industry, including mineral oil, alkylbenzene, and polyolester. No oil changes are required when retrofitting an existing R-22 system to R-453A. This allows an existing R-22/mineral oil system to retain its original oil once retrofitted to R-453A, preventing moisture sensitivity problems associated with newer or retrofitted systems incorporating polyolester lubricants.

Because R-453A is a 400-series refrigerant blend, it has fractionation potential and a temperature glide. To avoid blend fractionation, R-453A should be charged into the system as a liquid instead of a vapor. However, if the entire contents of the cylinder are to be used in the charging procedure, vapor charging can be performed. Just be aware that all the refrigerant in the cylinder must be used in charging the same system when vapor charging, otherwise fractionation can occur.

R-453A is a safe refrigerant blend and can be both recovered and reclaimed. Leak detectors used for any HFC-based refrigerant can be used for R-453A. Capillary, fixed orifice, or variable expansion refrigerant metering devices can be retrofitted with R-453A without any lubricant or hardware changes. Also, the same service equipment can be used with R-453A as with R-22.

THE RETROFITTING PROCEDURE

Below is a brief list of retrofit guideline procedures for converting an R-22 system to R-453A.

As with any refrigeration or air conditioning system being retrofitted, always follow the detailed retrofit guidelines from the equipment or refrigerant manufacturer.

1. Establish baseline data with temperatures, pressures, superheat, and subcooling;
2. Record compressor oil level and refrigerant charge;
3. Recover the R-22;
4. No oil change is needed. However, if polyolester lubricant is used to replace the mineral oil or alkylbenzene lubricant already in the system, replacing the o-ring seals before starting the system is recommended;
5. Evacuate the system to 200 microns, and charge the system with R-453A to 90 percent of the original R-22 charge;
6. Start the system, and take a system check. Record pressures, temperatures, superheat, and subcooling. Compare to baseline data. Adjust the thermal expansion valve (TXV), pressure controls, evaporator regulator, and/or condenser controls to maintain desired temperatures;
7. Check the system charge, and add refrigerant if needed to reach the original charge level;
8. Carefully monitor the oil level in the compressor. Add or remove more oil if required to maintain the correct level;
9. In systems with receivers or long and complex piping where oil return to the compressor could be an area of concern, the replacement of up to 25 percent of the oil charge with a polyolester lubricant is recommended;
10. Check the system for leaks; and
11. Label the system with the new refrigerant.  

Publication date: 1/8/2018